This article is the first part of a two-part series that provides you with a step-by-step solution for configuring Microsoft Forefront Threat Management Gateway 2010 as a reverse proxy that provisions remote access for Lync Web App conferencing users. Part two explains the type of network connectivity that is required to adequately use all the conferencing features of the remote Lync Web App client.

This article is being reviewed and updated. We will repost the article when revisions are complete.

I know that the post is old, anyway, you need to enable the option to “Forward the original host header instead of the actual one specified in the Internal site name field on the previous page” when creating the Reverse Proxy Web Publishing rule.

If you don't do that, you have a blank page calling meet, dialin and so on.